Agricultural harvester/threshers or "combines" are typically equipped with harvesting "headers" which include a cutter mechanism for cutting the crop and a feeder mechanism which feeds the cut crop into the combine feeder housing mounted on the front of the combine. The cut crop material is introduced into the combine via the feeder housing where the grain is threshed and separated from the plant residue. Such combines are required to operate over a wide variety of terrains, e.g. level fields, side sloping fields, rolling hills, etc. It is important that the header be positioned parallel to the terrain or as nearly parallel as possible such that the crop is cut at a consistent height above the ground. This means that the header must often be tilted with respect to the remainder of the combine.
A variety of lateral tilting mechanisms have been devised for tilting combine headers. These mechanisms have typically been unduly ponderous and complex, and thus prone to failure in the demanding environments to which they are subjected.
An early example of such prior art header lateral tilt mechanisms is U.S. Pat. No. 3,731,470 ("the '470 patent) to Cornish et al. and entitled SELF-LEVELING COMBINE. The '470 patent teaches a complex lateral tilt mechanism with a pair of tilt cylinders which collectively, selectively tilt the "crop gathering unit". Several guides are provided for supporting a pivot member, including left and right bolt and ferrules riding in corresponding slots and with U shaped guide members cooperating with pairs of upper and lower rollers on each side of the lateral tilt mechanism.
Another example of header lateral tilt mechanism is taught in U.S. Pat. No. 4,253,295 ("the '295 patent") to Knepper and entitled LATERAL FLOAT MECHANISM FOR COMBINES. This patent describes a combine header lateral tilt control mechanism and teaches a cradle assembly attachable to the combine header and pivotably attachable to an "attachment face" of the combine. A pivot control means selectively controls the extent of pivotal movement between the cradle and the attachment face. A header attachment plate is selectively pivoted about a pivot dowel and a pair of through bolts extending through slots in the attachment plate keep the plate and the attachment face in close proximity.
In a system such as is described in the '470 patent, the complexity of the operating mechanism, including a large number of moving parts and twin operating cylinders, is a detriment since there are so many parts subject to failure or jamming with debris. In the '295 patent, the provision of a single pivot pin to both support the header attachment plate and provide the pivot axis therefore, places too much stress on a single dowel.
It is clear then, that an improved combine lateral tilt assembly is needed. Such an assembly should be simple and economical, yet rugged and durable, and should utilize a minimum of moving parts subject to contamination or failure.